In-situ synthesis of AP@Co/BIM composites with improved thermal performance and anti-hygroscopicity

Abstract

Reducing the hygroscopicity and thermal decomposition temperature of ammonium perchlorate (AP) is of great significance for its application in solid rocket propellants. The AP@Co/BIM composites was prepared in this work by the coordination reaction of benzimidazole (BIM) and Co2+ on the surface of small-size AP (s-AP) particles, which can significantly reduce the hygroscopicity and improve the thermal performance of s-AP. The prepared AP@Co/BIM composites were characterized by scanning electron microscopy, infrared spectroscopy, x-ray diffraction, differential scanning calorimeter, thermogravimetric analysis and contact angle measurement. The results show that a dense and uniform Co/BIM complex is successfully coated on the surface of s-AP particles. Compared with the s-AP, the decomposition peak temperature of AP@Co/BIM decreases by 75.3 °C when the coating content is 25 wt% and its contact angle with water increases by 69.25°. At the same time, the hygroscopicity test shows that the moisture content of s-AP is only 3.2% of the s-AP after being placed at a relative humidity of 88% for 72 h. In addition, the burning rate of AP@Co/BIM based propellant increases by 5.28 mm s−1 compared with that of the s-AP. This study provides a reference for improving the thermal property and reducing the hygroscopicity of s-AP. It also has a certain application prospect in improving the combustion performance of propellants.